Many petrochemical plants handle invisible gaseous hydrocarbons. Most of these gases pose some sort of safety aspects. They may be toxic, or can cause health issues in case of long term exposure. Others are highly flammable, explosive even, and most of them will have a negative impact on the environment if they enter the atmosphere in large quantities. That is why leak detection is of vital importance in these petrochemical plants.

One of such plants is the Borealis highpressure, low-density polyethylene (LDPE) plant in Stenungsund, Sweden, which produces LDPE products for the cable and wire sector and has an annual production capacity of 350,000 tonnes. The Borealis cracker facility delivers the main ingredient: ethylene, which is converted into polyethylene in a high-pressure polymerization process.

Ethylene is a highly flammable hydrocarbon. To further increase the safety within the plant and reduce the environmental impact, Borealis has purchased an optical gas imaging camera from FLIR Systems. With this gas leak detection tool Borealis ensures that no gas leak escapes the attention of the process operators.

An optical gas imaging camera is a quick, non-contact measuring instrument that can visualize gas leaks in real time. Where many other measuring instruments only present the inspector with a number, optical gas imaging cameras present visual information, making the leak detection process more intuitive. Optical gas imaging cameras can also be used in hard-to-access locations, since they can detect small leaks from a distance. “When we started testing this relatively new technology I was at first very skeptical”, says shift supervisor LDPE Jan Åke Schiller. “But seeing these optical gas imaging cameras in action I quickly realized that they had an immense potential for leak detection here at the polyethylene plant and in petrochemical plants in general.”

Shift supervisor LDPE Jan Åke Schiller was skeptical at first, but is now convinced of the potential of optical gas imaging cameras.

Advantages of Optical Gas Imaging

Before the purchase of a FLIR GF306 optical gas imaging camera Schiller and his colleagues used so-called ‘sniffers’, devices which measure the concentration of a certain gas in one single location and generate a concentration reading in parts per million (ppm). “The main advantage of the optical gas imaging camera is that it provides you with the possibility to detect gases visually”, says Schiller. “Where sniffers just give you a number, an optical gas imaging camera allows you to detect gas leakage anywhere within the field of view of the camera. This speeds up the inspections considerably. Now that we have the optical gas imaging camera we do a quick scan at every startup. With a quick scan we cover approximately 80% of the entire plant in about thirty minutes. You would need a team of ten people with sniffers to work for two full days to reach the same result.”

Leaks show up in the optical gas imaging footage as a smoke like vapor.